This invention relates generally to the field of display of video images on interlaced raster scan displays. More particularly, this invention relates to a flicker filter for an interlaced raster scan video display.
Interlaced display systems such as those used for television are generally well suited for display of images such as general television programming images. They are not so well suited for display of certain types of computer generated images such as web pages, text, windows and web page content. The interlaced raster system of such display systems produce a phenomenon known as xe2x80x9cflickerxe2x80x9d. Flicker is caused by the interlacing of adjacent lines of the image, which for television type displays, occurs at a relatively low frequency. With certain types of displayed content, flicker becomes quite noticeable and disrupts the ability of the viewer to enjoy the viewing experience.
In order to reduce flicker, a filter known as a flicker filter has been used. Such filters reduce the flicker effect by removing components of the image which are most affected by flicker, or alternatively, by blurring the lines of an image to reduce sharpness. Most such techniques enhance the ability to view the image being displayed from a perspective of flicker reduction. This reduction in flicker is, of course, at some cost in sharpness or resolution, however, the resulting perception of flicker in the image can be dramatically reduced.
As television type displays become more widely used for display of computer information the role of the flicker filter becomes more critical. Various flicker filters have been developed with different algorithms and filter characteristics to deal with flicker. Unfortunately, no one set of filter characteristics is known to optimally deal with flicker in all image types. A filter which is optimized for text, for example, might not be well suited for certain types of graphic images.
The present invention relates generally to video displays. Objects, advantages and features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the invention.
By way of summary and not limitation, certain embodiments of the present invention relate to a method and apparatus for providing a flicker filter for an interlaced video display. Content is analyzed to determine what type of filter or filter characteristics selected from a plurality of available filters or filter characteristics can provide the better display of the content. Based on this analysis, the filter characteristics are selected and used for flicker filtering the content for display. The analysis can, for example, be based upon a font type, font size, language type or graphics objects.
According to one embodiment, a flicker filter for a video display receives content for display on said video display. A flicker filter having a plurality of selectable filter characteristics is provided. A content analyzer analyzes the content to determine which of the plurality of filter characteristics to use for flicker filtering the content.
According to another embodiment consistent with the invention, a flicker filter for a video display receives content for display on said video display. A plurality of flicker filters each has respective filter characteristics. A switch is coupled to the filters for selecting one of the plurality of filters for filtering of images to be displayed on the video display. A content analyzer which analyzes the content to determine which of the plurality of filters to use for flicker filtering said content.
A method of providing a flicker filter function to a video display consistent with embodiments of the invention include receiving content to be displayed on the video display; analyzing the content to be displayed; and selecting a filter characteristic for flicker filtering based upon the analysis of the content.
Another method of providing a flicker filter function to a video display consistent with embodiments of the invention include receiving content to be displayed on the video display, the content comprising a graphics script file; analyzing the content to be displayed by determining a font type, a font size, and a language and by analyzing a graphic object; selecting a filter characteristic by selection of a filter algorithm and a plurality of filter coefficients from a lookup table for flicker filtering based on the analysis of the content; filtering said content using the selected filter characteristics; and displaying the content on an interlaced display.
A method and apparatus for providing a flicker filter for an interlaced video display is provided in accordance with embodiments of the invention. Content is analyzed to determine what type of filter or filter characteristics selected from a plurality of available filters or filter characteristics can provide the better display of the content. Based on this analysis, the filter characteristics are selected and used for flicker filtering the content for display.
The above summaries are intended to illustrate exemplary embodiments of the invention, which will be best understood in conjunction with the detailed description to follow, and are not intended to limit the scope of the appended claims.